Carrier Heat Pump

You /do/ want the indicator on to keep you informed.

Also , where are you located? Heat pumps are not a great idea if you live in the US Northern states.

If you're going to own a house, you should learn to be comfortable with low voltage wires. if it's a new thermostat, you have the instructions for it, right?

I think the thermostat uses 14 volts but even if it's 20, you can't hurt yourself with that even if you held the wires in your wet hands. Even if you put them all in your mouth (though I'm not recommending that.) You'd get a tingle and your tongue would jerk back, but even if you could force your tongue to stay there, I don' tthink you could hurt anything. (I don't force my tongue to stay on even low votlage electric wirees.) Just write down what color wire went to what number screw before you disconnect anything (you shouldnb't have to disconnect anything, unless it's just one wire that goes somewhere else. More likely there will be an unconnected wire you have to connect. Also learn to make drawings, of all the screws with what color wire goes to each. Drawings are very important. It's easy to forget without them.

Do the instructions say which wire goes to the light indicator? If not call the guy and ask him and tell him you a) didn't have enough time to give a good answer (if you want to sort of blame him) or b) you made a mistake when you told him to disconnect the light (maybe a better approach since people like humility) And you'd be happy to connect it yourself if he'd tell you which wire and which screw. If he says he will do it, ask the charge. He may say free, esp. if he is near your house at times. If he wants more than you want to pay, say you canb't allocate more money to this, and maybe he'll do it for free or at least he'll answer your question.

You have to wonder about the competence of an installer that would put in a new heatpump system where it puts on auxillary heat when it's 47 outside. And maybe the design of a system or thermostat where it puts it on for

Whether she can figure out where the wire goes and do it herself, IDK. If it's a commonly available thermostat, there should be install instructions on the web. However if it's a Carrier one that's only dealer installed, etc, may not be able to find it.

I would definitely want the indicator on. Can't imagine why she told him to take it off. That he wanted to take it off is yet another sign to me that I wouldn't want this guy installing anything for me.

Might want to do some research before encouraging others to start working on their own wiring. I installed furnaces for six years, and all the low voltage thermostats I did were nominal 24 VAC, and often you'd see 26 or 27 on a VOM. Since you don't know the typical low voltage for stats, do you REALLY think you should tell people to work on them....

I'm wondering if this could be defrost cycle. The 3 minute thing sounds like it might be. On my HP/propane furnace, it will sometime, but not always do that, and then switch back to straight HP. Actually, the unit is running in AC mode using the aux heat (propane in my case) to evaporate any ice on the outside unit. I think the unit guesses, based one outside temp and maybe other factors, how often to de-ice. Much depends on the outside humidity, too. In my case, it seems to do it way too much, but the alternative, ice build up, wouldn't be good. So I figure they error on the side of safety.

Two things. It's my understanding that heat pumps just reverse the compressor flow to heat the outside coil for defrosting. Do they turn on aux heat at the inside unit while doing that? I never really thought about it but I guess it might be needed. Otherwise you'd get cold air blowing into the house. So the short 3 min aux heat cycle sounds like it could be that.

But even if that is the case and it was set wrong, it seems kind of strange to have the defrost cycle even able to be set at 47F and above, no? You would think that the setting range would be a lot lower to avoid problems like this.

On my HP/propane furnace, it will sometime, but not

IT really depends on your thermostat. We had a new heatpump with electric backup heat installed in a rental property a couple of years ago. A new programmable thermostat was included. We discovered that the backup heat would come on if the thermostat discovered the room temperature was more than 2 degrees lower than the set point of the thermostat.

We had the same type programmable thermostat installed in our current mfg. home with heat pump. Same thing with the thermostat. More than one degree difference and the backup heat comes on.

The reason is efficiency. The least cost heating is to maintain the same temperature night and day. The heat pump will do this best when the set temperature and the room temperature remain the same.

Set your thermostat to the temperature you want, for every day of the week, both night and day. A one degree lower night temp will keep the backup off, but will run the heatpump steady until the house temp comes up to the daytime temp.

The heating company will not tell you this up front.

Paul

I think you should have him come back out and reset it so the aux indicator light comes on. Should be no big deal and since it is a new system they should have no problem doing that for you. Even if you could figure out how to do that change yourself, I think that you would be better off having the installation company tech do it. That way, they won't be able to say that you messed something up by working on it yourself (even if you didn't).

Also, there is an alt.hvac Usenet newsgroup in case you want to try your post there. It used to be an awful group full of nasty morons, but lately it seems more sane and sometimes helpful.

Let us know what you end up doing and what the outcome is on this.

Only if aux heat, eg electric has to kick in to get the temp back up. Otherwise, with say a nat gas or oil furnace, cost is lower if you set it back at night. If you can't set it back, then you're going to be needing to supply more heat to the house to keep it maintained constantly. That's a negative.

The heat pump will do this best when the set

I'd want to know but that's your decision.

Smart thermostats can control the aux heat usage. Mine is set up to run without aux for two hours before turning it on[*]. It would be better to know the outside temperature but I don't have that option.

You're going to get hurt on 26-27V? It's pretty easy and safe if YOU'RE SURE IT'S A LO VOLTAGE SYSTEM. Some aren't (though a heat pump's thermostat should be).

The bigger danger is shorting the 24V supply and blowing a fuse in the air handler, or worse. BTDT. Just follow the instructions and it's not difficult or dangerous.

That's not all that unusual. A new thermostat is in order.

That's ridiculous. The thermostat wouldn't last the week.

Not believing it. Heat pumps can take a long time to recover in really cold weather but in somewhat warmer weather there is no reason to waste the energy. I prefer it colder at night that during the day. Any system that didn't allow me the flexibility would soon be gone.

So what? That's true of any system. That's how thermostats work.

Any idiot should know how a thermostat works.

Good points. Noted.

yes if you decide to wire it yourself, turn off the power to protect the eq uipment.

also, no one mentioned that most heat pump systems use a 2 stage thermostat . If the room is only a little cooler then the set point, the heat pump co mes on for stage 1. But if the room is more then 2 or 3 deg cooler than th e set point, like when you first turn up the heat, then stage 2 will come o n (the aux heat will come on). This is normal. Think of it a 2 thermostat s, stage 1 is set for the setting you see, and stage 2 is set a few degrees below that. Once you understand that, if you want to keep the aux stage 2 heat from coming on, you make smaller increases in the setting. If you ma ke a big increase in the setting, the aux heat will come on and that is no rmal.

When it is below about 32 outside and damp, I turn off the heat pump to avo id the defrost business, but I have oil for the aux heat so its not so expe nsive.

Mark

Mark

That's the point. The second stage is often resistive heat. It's better to avoid that, if at all possible. Smart thermostats allow one to disable the second stage unless it's really needed.

Most homes don't have such backup heat. It's not warranted where heat pumps are most useful.

At the price of oil, I would think it would be much more expensive to heat with oil unless it got below 25 deg or lower.

Of course that depends on the local price of electricity, but it sure would here. It so rarely gets below 25F for any period of time that backup heat is senseless (at least as a cost savings).

agreed, and that is what I said except at 32 instead of 25. Below 32 if you account for the inefficiency of the defrosting and the wear and tear on the compressor and the discomfort of being cold in the house, it starts to pay to burn some oil.

I'd like to see someone develop a solar assisted heat pump. Use some solar heat to get the air up to 32 so the heat pump can work well.

Mark

Mark

Instead of wasting money on a solar assisted heat pump (daytime is not when you need the heat) why not do something useful and buy a ground-source heat pump?